USRE22364E - Circuit controller - Google Patents

Description

Aug. 10, 1943.

C. STANSBURY CIRCUIT CONTROLLER Original Filed May 2, 1958 Reissued Aug; 10, 1943 R 22,364 OFFICE omourr coiv'rnonma can-bu Stansbury, Chevy chm, Ma, asslgnor to Cutler-Hammer, Inc.,-Milwaukee, Win, a

corporation of Delaware Original No. 2,216,329, dated October 1,1940, Serial No. 205,492, May 2, 1938. Application for reissue June 13, 1942, Serial No. 146,310

'14 Claims.

This invention relates to a circuit controller, and more particularly to a resistance welding controller by means of which it is possible to apply the welding current to an individual spot to be welded an adjustable number of times in rapid succession.

In spot welding metals it is desired to apply to grammatically a system incorporating the present a spot which is to be welded a relatively large current for a very short time so that the energy which is dissipated in the weld is concentrated as much as possible in the spot and that dissipation of energy into the surrounding metal and the resulting heating thereof is held down to a minimum. This is particularly necessary when welding materials the physical characteristic of which is unfavorably affected by heat. By concentrating the heating efiect of the welding current to the weld undesirable changes in the structure of the material adjacent to the weld are avoided.

With very heavy material the amount of energy thus reouired must all be supplied in a very short period of time and the transformer which supplies the energy must therefore have a very large current capacity in order not to cause too great a drop of the welding voltage which would tend to reduce the effectiveness of the welding operation. The electrodes also heat up unduly and tend to fuse to the material to be welded. In order to F overcome these disadvantages the present system provides for the supply of the total energy necessary to produce the weld in a series of current impulses of relatively low magnitude. This permits the heat developed in the electrodes themselves to bedissipated by the cooling medium of the electrodes and the cool electrodes intum absorb the heat diffused to the surface of the metal and which is not consumed in softening and melting the metal at the interface between the two parts to be welded. Thus undesirable changes in the structure of the welded material beyond the weld are avoided. The repeated application of the welding current takes place in rapid succession, while the number of pp c of welding current as well as the duration of the individual shots and the interval between successive shots may be regulated to suit particular requirements and the capacity of the weldin transformer.

An object of the invention is to provide a welding controller for applying an adjustable number of current impulses to a weld.

Another object 'is to provide a controller of the aforementioned type by which the duration of the individual impulses and the intervals between impulses are individually adjustable.

Another'object is to provide an improved electromagnet repeating mechanism suitable for such welding control and other purposes. The accompanying dra'wing illustrates diainvention.

Referring to the drawing the system is supplied with current from bus bars of an altemating current source, represented by lines L and L", which furnish welding current to a transformer I having a primary winding i" and a secondary winding l The secondary winding l is connected to: the welding electrodes 2. In series with the primary winding I are the normally open contacts of the magnet switch 3 which has a magnetizing winding 3. The winding 3 is connected across the lines L and L in series with normally 'open contacts 4 of an electromagnetic relay l which is provided with an operating winding 4'; The winding 4* in turn is connected across the lines L and L? through normally open contacts 5 of an electromagnetic relay 5 which relay is further provided with normally open contacts 5, normally closed contacts 5 and an operating winding 5 The normally open contact 5 connects a closing "winding '6" of an electromagnetic switch 6 across lines L and L while an opening or lockout winding 6' of switch 6 is energized from the lines L and L when the contact 5 is closed. Relay 6 is equipped with a normally open contact S and a normally closed contact 6". paralleled by an adjustable condenser I while the lockout winding i is paralleled by an adjustable condenser 8.

The aforementioned line or bus bar L is connected to the bus bar I through a rectifier 9 of any suitable type. Thus the bus bars L and L form the terminals 'of a direct current supply which receives its energy from the alternating current source through the rectifier 9. In th present system a half wave rectifier 9 is shown but it is obvious that a full wave rectifier may be employed in order to smooth out the voltage variations due to the half wave rectification. In

the system represented by the drawing the voltage fluctuations are smoothed out by a condenser ll) of suitable capacity which is connected between the bus bars L and L This condenser maintains the direct current voltage at a substantially constant value in a well known manner.

The system also further includes a relay ll having an energizing winding ll, normally open contacts II and ll and normally closed contacts II. A pressure operated switch I 2 actuated from the hydraulic system which also controls the movement of the welding electrodes 2 in a well known manner is provided with normally open contacts I! which contacts close when the pressure in the system and hence between the electrodes reaches a certain value. There is provided a pilot pushbutton l3 havin normally open contacts l3 and normally closed contacts li This push button is manually con- The operating winding 6' is trolled by the operator and is depressed when it is desired to produce a weld.

To regulate the number of current impulses which are delivered to an individual weld a relay I4 i provided. The relay I4 has a ratchet I4 which is engaged by a pawl MP. The pawl may be released by energization of anelectromagnetic winding I4 whereupon the relay drops by gravity. A solenoid winding I4 when energized operates a ratchet pawl I4 which engages with ratchet I4 and lifts the ratchet by one tooth at a time. When the coil I4 is deenergized the pawl I 4 is moved out of engagement with the ratchet I4, but the ratchet is held in the position to which it has been moved by engagement with the pawl I4 An extension I4 of the ratchet is provided with an adjustable collar I4 which in the highest position of the ratchet engages the bridging contact of normally closed contacts I4 and opens said contacts. The winding 14 may be connected in series with a resistor I5 and the normally open switch 6 across the lines L and L There is also'a circuit from the line L through the normally closed contact I3 the winding I4 and normally closed contacts II to line L. Another circuit extends from the' line L through normally closed contacts I4 norma1- 1y open contacts I3, winding I I to line L Winding II is paralleled by an adjustable condenser I6. Normally open contacts I 3 are paralleled by the normally open contact II A relay I1 has an energizing winding I! which may be connected in series with contact I4 and contact II across the lines L and L The relay I! has normally open contacts Il and normally closed contacts I'I. The hydraulic cylinder which operates the welding electrodes (not shown) is controlled by two ,valves, an on valve which moves the electrodes to closed position and which is controlled by an electromagnet I8 and an ofP valve which is controlled by an electromagnet I9. The "on magnet I8is connected in series with the normally closed contacts 2|! of an emergency push button switch 20 which is also provided with normally open contacts 20'. A circuit extends from line L through contacts I 4 contacts II contacts 20, through winding I8 to line L, while a second circuit extends from line L through contact I4, contact 20 or contact I! through winding I9 of the oil valve to line L The operation is as follows: When the system is at rest the apparatus is in the position shown in the diagram except that normally the relay I4 is in its lowermost position. Therefore a circuit is established from line L through contact I4 contact ll, coil I9 to line L The "off valve is therefore open and the electrodes 2 are separated by the hydraulic system. Current is supplied to bus bar L through the rectiller 9. It will be observed that in the inoperative position the contact I3 of the push button switch I3 is closed so that a circuit is completed from the line L through contact I 3, operating coil I4, contact II to line L. This energizes the winding I4 releasing the latch I4, so that the relay I4 drops to its lowermost position.

If now the operator wishes to start the equip- 1 ment he momentarily presses the button I3 and circuit is thereby established from the line L to contacts I3, operating coil II to line ,L through rectifier 9 and the relay II is energized thereby opening the normally closed contact II and closing the normally open contacts II and II. The closure of the contact II establishes a maintaining circuit for the relay coil II so that the latter remains energized independently of the contact I3 as long as the contact I l is closed. Circuit is also established from the line L through contact I4 contact II, coil I! to line L. This energizes relay I1 and opens contact H and closescontact Il The opening of contact I! deenergizes the oil" valve of the hydraulic system and energizes coil I8 thereby operating the "on valve of the hydraulic system so that pressure is applied to close the electrodes 2. At the same time contact II is open there by deenergizing coil I4 and permitting the latch I4 to engage the ratchet I 4*.

After the electrodes 2 have closed and produced suflicient pressure on the material to be welded the pressure switch I2 closes the contact I 2*. This energizes the winding 5 thereby opening the normally closed contact 5 and closing the normally open contact 5". As long as the contact 5 is closed the coil 6 is energized thereby opposing the lifting of the relay 6. When contact 5 is open the coil 6* is deenergized but the current therein will not die out instantaneously but will continue to flow for some time due to the action of the condenser 8 and thus will resist the operation of relay 6. The duration of this resisting force depends upon the adjustment of the condenser 8. At the same time that coil 6' is deenergized coil ii will be energized and after the pull of the coil E has been reduced a suificient amount the coil 6 will pull the relay 6 upward thereby closing contact 6 and energizing coil I 4 of the ratchet solenoid. The solenoid will operate and lift the relay I4 by one tooth of the ratchet. At the same time contact 6 is opened thereby deenergizing the relay 5 and this causes deenergization of the coil 6 and energization of the coil 6*. The relay Ii however cannot drop immediately due to the delayed decay of the flux in the coil 5", the time of which is determined by the adjustment of the condenser 1.

After the expiration of some time the magnetism produced by the coil Ii is insufiicient to hold the coil in its upper position and the relay will drop again. The dropping of the relay opens the contact 6 thereby deenergizing the magnet I4 and the pawl of the ratchet I4 drops outof engagement with the ratchet I4, but the relay I4 will not drop back to its initial position a it is held bythe engaged latch I4 It will be observed that every time the relay 5 is raised to its uppermost position it closes contact 5 which energizes coil 4 of rela 4 thereby closing contact 4 which controls the coil 3 of main switch 3. Thus upon each energization of the relay 5 the main switch 3 closes'the primary circuit of the transformer through the contacts 3 and permits a current impulse through the welding transformer. This cycle is repeated until the collar I4 engages the contact I4 whereupon thelatter contact is opened thereby causing deenergization of the coil II and the'resultant closure of contact I I I3 is in its released position the coil I4 of the latch I4 is energized permitting the relay I4 to drop back to its initial position. The opening of the contact I4 also deenergizes the relay I! so that the latter causes energization of the "01? magnet of the hydraulic system and deenergization of the on magnet thus returning the electrodes 2 to the .work piece. The opening of the contact I4 of course also discontinues power supply to the relays Sand 6 so that the alternate operation there- As the push button switch off position and releasing the p 22,364 s V of and the resulting energization of the main switch 2 and of the ratchet coil ceases. By

adjustment'of the collar I the number of current impulses during acycle canbe adjusted as is obvious.

It during an operating cycle the operator should desire tointerrupt the working the machine he may press the push button 20 thereby opening the circuit-oi the on solenoid and closing the circuit oi. the "oil" solenoid, thus causing release 01' the work piece by the elec-,

trodes. This operation of course also causes opening of the switch I! due to the decrease of ,cation of said mechanism, electrostatic means effective to maintain energization of each of said magnets for a temporary period after its disconnection from said circuit, .an electromagnetic relay normally biased to one position and having a switch for effecting the connection to said circuit of one of said electromagnets in said one position and interrupting it in another position and having another switch for interrupting the connection to said circuit of the other of said magnets in said one position and completing it in said other position, and a contact for energizing said electromagnetic relay to move it to said other position, said lost contact being biased to its closed position by said mechanism when the latter is near its one limit of travel.

2. In a controller for controlling an adjustable number of current impulses supplied to a translating circuit whereby the duration of the impulse and the interval between impulses are individually adjustable, in combination, a reciprocating mechanism comprising two electromagnets adapted to be alternately connected to.

a circuit to effect reciprocation of said mechanism, electrostatic means effective to maintain energization'of each of said magnets for a temporary period afterits disconnection from said circuit, means to connect said magnetsalternately to said circuit and then disconnecting each upon connection of the other, said mechanism under the influence of said electrostatic means, having a minimum time element incident to each reciprocation without dependence therefor upon circuit to effect reciprocation 01' said mechanism, electrostatic means eflectiveto maintain energization of each of said-magnets for a temporary period after its disconnection from said circuit, an electromagnetic relaynormally biased to one position and having a switch for eflecting the connection to said circuit of one of said electromagnets in said one position and interrupting 3 another position another switch itin the other of said magnets .in said one position and completing it in said other position, a contact ,5 for energizing said electromagnetic relay to move it to said other position, said contact being biased to closedposition by said mechanism when the latter is near its one limit of travel, and-a con trol switch in a circuit actuated by said relay'.

' number of current impulses supplied to a translating circuit, whereby the duration of the impulse and the interval between impulses are individually adJustable in combination, a. reciproeating mechanism comprising two electromag- .nets adapted to be alternately connected to a circuit to efiect reciprocation of said mechanism, electrostatic'means efl'ectiveto maintain ener-,

gization of each oisaid magnets for a temporary period after its disconnection ,from said circuit, means to connect said magnets alternately to said circuit'and then disconnecting each upon connection of the other, said mechanism under the influence oi. said electrostatic means, having ciprocation without dependence therefor upon said last mentioned means, switch means for.

- opening and closing a translating circuit in re.-

sponse to the reciprocations of said mechanism. and means responding to a given number of cycles of operation or said reciprocating mechanism to terminate the current supplied to said mechaism and said switch means.

5. In a controller for controlling an adjustable number of current impulses in a translating circuit, whereby the duration of the impulse and the interval between impulses are individually adjustable in combination, a reciprocating mechanism comprising two electromagnets adapted to be' alternately connected to a circuit to elect reciprocation of said mechanism, electrostatic means eflective to maintain energization of each of said magnets for a temporary period after its disconnection from-said circuit, an electromagnetic relay normally biased to one position and having a switch for effecting the connection to said circuit of one of said electromagnets in said one position and interrupting it in another position and having another switch for interrupt ing the connection to said circuit or the other of said magnets in said one position and completing it'in said other position, a contact for energizing said electromagnetic relay to m'ove'it to said other sition by said mechanism when the latter is near its one limit of travel, a control switch in a translating circuit actuated by said relay, and

means responding to a given'number ofcycles of operation of said reciprocating mechanism to terminate the current supp yto said mechanism and said control' switch. y

6. A control system for an electricwelder having electrodes adapted to 'be clamped against the to perform the welding operation, comprising means for initiating the pressing of said electrodes against work to be welded, means for periodically energizing said welding electrodes, means" ior counting the number of impulses transmitted to the electrodes, and means for discontinuing the current impulses after apredetermined number have been transmitted, said counting means being readily adjustable to selectivelyvary the number of impulses transmitted.

for interrupting the connection to said circuit bf 4. In a controller for controlling an adjustable position, said contact being biased to closed work and 'to transmit current through the work" Y 7. A control system for an electric welder having electrodes adapted to be clamped against the .work and to transmit current through the work to perform the welding operation, comprising means for initiating the pressing of said electrodes against work to be welded, means for transmitting a series of current impulses through the work between said electrodes, means for adjusting the duration or the current impulses and oi! the periods therebetween independently of each other, means for discontinuing said current impulses after a predetermined number has been transmitted through the work including means for selectively varying said number, and means for releasin said electrode pressure to complete the welding operation.

8. A control system for anelectric welder having electrodes adapted to be clamped against the work and to transmit current through the work to perform the welding operation, comprising means for initiating the pressing of. said electrodes against work to be welded; means for pressure and to transmit current through the work'to perform the welding operation, comprising means for initiating the supply oi fluid pressure to said electrodes to press them against'the work to be welded, means operable when a predetermined pressure on the electrodes has been attained to initiate the supply of welding current through the work, means for periodically interrupting and reestablishing said supply of welding current with on periods of common predetermined duration and "01? periods of common predetermined duration, means operating to discontinue the reestablishment of welding current i after a predetermined number of o11 periods have been effected including means for selectively varying said number, and means for releasing the electrode pressure to complete the welding operation.

10. A welder control system for electrically welding work by passing current therethrough between electrodes pressed against the work by the work and to transmit currentthrough the work to perform the welding operation, comprising means for initiating the pressing of said electrodes against work to be welded, means for thereafter initiating a series oi current impulses transmitted through the work between the electrodes, said last mentioned means having adJustable parts associated therewith for determining the duration of each of said current impulses, means for counting said current impulses and for discontinuing the series at the conclusion of a predetermined number 01' impulses including means for selectively varying said number, and means for releasing the electrode pressure to complete the welding operation.

12. A control system for an electric welder having electrodes adapted to be clamped against the work and to transmit current through the work to perform the welding operation, comprising means for initiating the pressure of said electrodes against work to be welded, means energizing the electrodes to pass current through the fluid pressure which comprises means for initiating the supply. of fluid pressure to said electrodes, cooperating contacts cyclically engaged and disengaged for periods of predetermined duration, means placing the supply of welding current through the electrodes in said cyclically operated contacts when a predetermined electrode pressure has been attained, means for coimting the number of current impulses transmitted through the work, as said contacts are thereafter work, a relay, means energizing said relay, means under the control of said relay for eii'ecting deenergization .01 the electrodes after a predetermined interval, means deenergizing said relay and reenergizing said electrodes and relay after a predetermined interval, and means for continuing. the energization and deenergization of said electrodes and relay for a predetermined number of electrode energized periods and for terminating the series after said predetermined number has been accomplished including means for selectively varying said number.

13. A control system for an electric welder having electrodes adapted to be clamped against .the work and to transmit current through the work to perform the welding operation, comprising means for initiating the pressing of said elec-' trodes against the work to be welded, means for periodically energizing said welding electrodes,

progressively movable means connected to be moved a predetermined distance in response to each electrode energization, means operated by said progressively movable means when it has moved a predetermined variable distance for discontinuing the energization of the electrodes, and means for selectively varying said distance to vary the number of electrode energizations effected.

14. A control system for an electric welder having electrodes adapted to be clamped against the work and to transmit current through the work to perform the welding operation, comprising means for initiating the pressing of said electrodes against the work to be welded, means energizing the electrodes to pass current'through the work, a relay, means energizing said relay,

means under the control of said relay for deenergizlng the relay and for reenergizing both the relay and the welder electrodes after a predetermined interval, means for continuing the energization and deenergization of said electrodes and relay, progressively movable means connected to be moved a predetermined distance in response to each electrode energization, mean for discontinuing the reenergizing of th electrodes and relay when said progressively movable means has been moved a predetermined variable distance,

and means for selectively varying said distance to vary the number of electrode energizations effected.

CARROLL STANSBTJ'RY.

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